In India, Cow is more of divine than Bovine. As author rightly mentioned "Agriculture-plus-dairying became the backbone", in Indian civilization, it has been imbibed in culture that they both go hand in hand.Their interdependence is well known Cow eats Grass/waste crops, Cow dung/urine is used as manure for the crop and mosquito repellants etc. And outputs of both are enjoyed by the farmer - Crop and Milk products :)
Up until recently, most of Indian farming depended on (and still does to a good extent) on Bulls ploughing the fields for seeding. That and bullock carts as transport.
Well, yes. You don't want one bull to do 100% of cows, but one bull can easily do an entire herd, and using In Vitro methods the most valuable bulls fertilise thousands of cows.